For most of us, the image above is simply the pound symbol. It's what we dial on the phone after making an entry or shorthand when writing down weights. But in the world of Twitter it is better known as the hashtag symbol.

So how do you use it? When writing a post or tweet you can use the hashtag to mark relevant words which makes your tweet more easily found in searches. To use the hashtag simply type it and then immediately follow it with the keyword (NO spaces!!!). For example, if you wanted to tweet something about marketing, you could #marketing and someone who searches it can find your tweet instead of it getting lost in the millions of tweets. If you want to use a string of words they need to be all connected. For example #lovemyboss pulls up all sorts of tweets. Hashtags are also useful for building conversations about something. For instance, a lot of events and shows are making hashtags so that viewers can talk about the event/show as it's happening. The NFL team the New York Giants is utilizing fans' Twitter posts during actual games. Learn more about that here. It’s important to not go overboard with the hashtags, though. Twitter recommends using no more than three per tweet.

There are many different hashtags used on Twitter. You can visit hashtags.org to see a list of all popular ones used.